Image pickup system and signal processing apparatus

ABSTRACT

An image pickup system includes: a camera including a first image pickup unit and a second image pickup unit; and a processor configured to: define a first common area in a first image and a second common area in a second image, respectively; detect brightness of an image in the first common area; detect brightness of an image in the second common area; adjust brightness of the first image based on the brightness of the image in the first common area; and adjust brightness of the second image based on the brightness of the image in the second common area.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of PCT/JP2015/084968 filed on Dec. 14, 2015 and claims benefit of Japanese Application No. 2014-253275 filed in Japan on Dec. 15, 2014, the entire contents of which are incorporated herein by this reference.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates to an image pickup system and a signal processing apparatus, and more particularly to an image pickup system and a signal processing apparatus that are capable of acquiring two picked-up images having parallax.

2. Description of the Related Art

Conventionally, an image pickup system capable of acquiring two picked-up images mutually having parallax, for example, an image pickup system configured to generate a three-dimensional image using two picked-up images having parallax has been known.

More specifically, an image pickup apparatus configured to pick up a three-dimensional image (3D image) using a plurality of image pickup portions is disclosed in Japanese Patent Application Laid-Open Publication No. 2012-065204 and Japanese Patent Application Laid-Open Publication No. 2001-148865. Each of the image pickup apparatus according to Japanese Patent Application Laid-Open Publication No. 2012-065204 and Japanese Patent Application Laid-Open Publication No. 2001-148865 is adapted to perform photometry of an image pickup signal outputted from each of two image pickup portions and control an exposure value of each image pickup portion based on a result of the photometry (a luminance value).

On the other hand, in specification of Japanese Patent No. 4955840, a three-dimensional endoscope configured to generate a three-dimensional image using two pick-up images having parallax in order to three-dimensionally observe a minute site of operation in a surgical operation in a body cavity is disclosed. The three-dimensional endoscope is provided with a pair of left and right observation optical systems and a pair of left and right image pickup portions corresponding to the observation optical systems.

Further, in specification of Japanese Patent No. 2716936, a three-dimensional endoscope configured to combine left and right image signals from two image pickup devices into one and perform image processing by one camera control unit is disclosed.

In the three-dimensional endoscopes as shown in the specification of Japanese Patent No. 4955840 and the specification of Japanese Patent No. 2716936, even though two image pickup portions are provided as described above, it is thought that one light source apparatus for illuminating an object in a body cavity is provided. That is, even if a light source of the light source apparatus is to be light-adjusted, it is thought that the number of light adjustment means is one.

SUMMARY OF THE INVENTION

An image pickup system of an aspect of the present invention includes: a camera including: a first image pickup unit configured to pick up an optical image of an object and generate a first image pickup signal representing a first image; and a second image pickup unit configured to pick up an optical image of the object and generate a second image pickup signal representing a second image having parallax relative to the first image; and a processor including hardware wherein the processor is configured to: define areas where an optical image of the object is picked up in common in the first image and the second image as a first common area in the first image and a second common area in the second image, respectively; detect brightness of an image in the defined first common area in the first image; detect brightness of an image in the defined second common area in the second image; adjust brightness of the first image based on the brightness of the image in the first common area; and adjust brightness of the second image based on the brightness of the image in the second common area.

A signal processing apparatus of an aspect of the present invention is a signal processing apparatus configured to process a first image picked up by a first image pickup unit and a second image picked up by a second image pickup unit, the second image having parallax relative to the first image, and the signal processing apparatus including: a processor including hardware wherein the processor is configured to: define areas where an optical image of an object is picked up in common in the first image and the second image as a first common area in the first image and a second common area in the second image, respectively; detect brightness of an image in the defined first common area; detect brightness of an image in the defined second common area; adjust brightness of the first image based on the brightness of the image in the first common area; and adjust brightness of the second image based on the brightness of the image in the second common area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external perspective view showing a whole configuration of an endoscope system of a first embodiment of the present invention;

FIG. 2 is a block diagram showing the configuration of the endoscope system of the first embodiment;

FIG. 3 is a front view of a distal end portion of an insertion portion of an endoscope in the endoscope system of the first embodiment;

FIG. 4 is a cross-sectional view of the distal end portion of the insertion portion of the endoscope in the endoscope system of the first embodiment;

FIG. 5 is a diagram showing operation of an area defining portion in the endoscope system of the first embodiment; and

FIG. 6 is a diagram showing a 3D composite image generation process in a conventional three-dimensional endoscope system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

An embodiment of the present invention will be described below with reference to drawings.

A configuration of an endoscope system of a first embodiment will be described with use of FIGS. 1 to 4. FIG. 1 is an external perspective view showing a whole configuration of the endoscope system of the first embodiment of the present invention; FIG. 2 is a block diagram showing the configuration of the endoscope system of the first embodiment; FIG. 3 is a front view of a distal end portion of an insertion portion of an endoscope in the endoscope system of the first embodiment; and FIG. 4 is a cross-sectional view of the distal end portion of the insertion portion of the endoscope in the endoscope system of the first embodiment.

As shown in FIG. 1, main portions of an endoscope system 1 of the first embodiment of the present invention are configured with a three-dimensional endoscope 2, which is a so-called 3D endoscope configured to generate a three-dimensional image by two image pickup units mutually having parallax, a processor 3 to which the three-dimensional endoscope 2 is attachably and detachably connected and which is configured to perform predetermined signal processing for image pickup signals from the image pickup units and is provided with a light source portion configured to supply illuminating light to the three-dimensional endoscope 2, and a monitor 5 as a display device configured to display an image signal generated by the processor 3 as an endoscopic image.

Note that, when the endoscope system 1 of the present embodiment is in an operation room, various kinds of medical equipment including the processor 3, for example, devices such as an electrosurgical knife device, a pneumoperitoneum device and a video recorder, and a gas cylinder filled with carbon dioxide are placed on a cart 9.

In the present embodiment, the three-dimensional endoscope 2 is a rigid endoscope applied to three-dimensionally observe a site of operation in a body cavity, for example, applied to an abdominal cavity procedure. The three-dimensional endoscope 2 is provided with a rigid insertion portion 6 which is an insertion portion to be inserted into a body cavity and which has a length applied to the abdominal cavity procedure, an operation portion 7 configured to be grasped by an operator and perform various operations of the three-dimensional endoscope 2, and a universal cord 8 extended from the insertion portion 7 and connected to the processor 3.

The insertion portion 6 is configured with a distal end rigid portion 11, a bending portion 12 and a rigid portion 13 coupled in that order from a distal end portion 6 a side toward a proximal end portion 6 b side. That is, a proximal end portion of the distal end rigid portion 11 is coupled with a distal end portion of the bending portion 12, and a proximal end portion of the bending portion 12 is coupled with a distal end portion of the rigid portion 13. Further, the rigid portion 13 is a rigid tube which is elongated and rigid, and a proximal end portion of the rigid portion 13 is coupled with the operation portion 7 as the proximal end portion 6 b of the insertion portion 6.

Further, as shown in FIGS. 2, 3 and 4, a left side image pickup unit 21L for left side image (left eye) and a right side image pickup unit 21R for right side image (right eye) are arranged in the distal end rigid portion 11 of the insertion portion 6 in order to three-dimensionally observe a site of operation.

The left side image pickup unit 21L is configured with an image pickup optical system 22L for left side image (left eye) and an image pickup device 23L, and the right side image pickup unit 21R is configured with an image pickup optical system 22R for right side image (right eye) and an image pickup device 23R.

Further, as shown in FIG. 4, each of both the image pickup optical system 22L for left side image and the image pickup optical system 22R for right side image is configured with an objective lens for observing a site of operation and an image forming lens for forming an image of the site of operation observed by the objective lens.

Furthermore, at image forming positions of the image forming lenses of the respective image pickup optical system 22L and the image pickup optical system 22R, the image pickup device 23L and the image pickup device 23R are arranged, respectively. Each of the image pickup device 23L and the image pickup device 23R is configured, for example, with a CCD image sensor, and each of the image pickup device 23L and the image pickup device 23R is adapted to photoelectrically convert an image (a site of operation) formed by the image forming lens after being transmitted through the objective lens of the image pickup optical system 22L or the image pickup optical system 22R, and generate a predetermined image pickup signal.

Further, on subsequent stages of the image pickup device 23L and the image pickup device 23R, correlated double sampling circuits (hereinafter referred to as CDS circuits) 26L, 26R and analog/digital conversion circuits (hereinafter referred to as A/D conversion circuits) 27L, 27R are provided, respectively.

The image pickup device 23L and the image pickup device 23R photoelectrically convert object images formed on image pickup surfaces and output image pickup signals to the CDS circuits 26L, 26R, respectively. The CDS circuits 26L, 26R perform correlated double sampling processing for the image pickup signals and output the image pickup signals to the A/D conversion circuits 27L, 27R. The A/D conversion circuits 27L, 27R are adapted to convert the image pickup signals from analog signals to digital signals and output the digital signals to the processor 3.

On the other hand, various cables 15 such as signal lines related to the image pickup device 23L and the image pickup device 23R are adapted to be connected to the processor 3 through insides of the insertion portion 6, the operation portion 7 and the universal cord 8. Further, a light guide cable 16 configured to transmit illuminating light from the light source portion of the processor 3 is inserted through the insertion portion 6, the operation portion 7 and the universal cord 8.

On a proximal end side of the universal cord 8, a light source connector 17 a, which is an end portion of the light guide cable 16, is arranged and is adapted to be attachably and detachably connected to a light source connector portion 30 a of the processor 3. On the other hand, a signal connector 17 b, which is an end portion of the signal cables 15, is arranged, branching from the light source connector 17 a, and is adapted to be attachably and detachably connected to a signal connector portion 30 b of the processor 3.

Further, as shown in FIG. 3, on a distal end face 11 a of the distal end rigid portion 11 of the insertion portion 6, an illumination window 25 is arranged at a position facing a distal end face of the light guide cable 16. Note that, in the present embodiment, two light guide cables 16 are provided, and two illumination windows 25 are arranged accordingly.

The light source connector 17 a is connected to the light source connector portion 30 a of the processor 3; illuminating light emitted from a light source portion 4 provided inside the processor 3 is transmitted via the light guide cables 16; and the illuminating light is emitted from the illumination windows 25 provided facing the distal end face of the light guide cable 16 on the distal end face 11 a of the distal end rigid portion 11.

On the other hand, on the distal end face 11 a of the distal end rigid portion 11, two observation windows 24L, 24R are arranged adjacent to the illumination windows 25 so that an optical image of an illuminated object such as an affected part is inputted. Note that the observation windows 24L, 24R are arranged at positions facing the image pickup optical system 22L and the image pickup optical system 22R described above, respectively.

Further, as shown in FIG. 4, the three-dimensional endoscope 2 has a containing portion 29L for left side configured to contain the left side image pickup unit 21L and a containing portion 29R for right side configured to contain the right side image pickup unit 21R. Note that the containing portion 29L and the containing portion 29R are separate bodies, respectively.

Note that, though such a 3D endoscope is adopted that optical images mutually having parallax are inputted to the two left and right image pickup optical systems 22L and 22R to generate a left-side optical image and a right-side optical image, which are separate optical images, respectively, and the left and right separate optical images are photoelectrically converted by the separate image pickup device 23L and the image pickup device 23R, respectively, in the present embodiment as described above, this is not limiting.

That is, it is also possible to arrange one image pickup device at the image forming positions of the respective image forming lenses of the image pickup optical system 22L and the image pickup optical system 22R so that left and right separate optical images are formed in different areas on a same image pickup surface of the one image pickup device.

In this case, the processor 3 configured to perform signal processing of image pickup signals outputted from the one image pickup device can process the image pickup signals of the different areas on the same image pickup surface as left and right optical images.

Further, though CCD image sensors are adopted as the image pickup device 23L and the image pickup device 23R in the present embodiment, this is not limiting, and, for example, CMOS image sensors are also possible.

Next, the processor 3 in the endoscope system of the present first embodiment will be described in detail.

As shown in FIG. 2, the processor 3 in the present embodiment has a controlling portion 31 configured to control various circuits in the processor 3; a first signal processing portion 32 configured to, when an image pickup signal generated by the image pickup device 23L for left side image and passing through the CDS circuit 26L and the A/D conversion circuit 27L (hereinafter a first image pickup signal) between two image pickup signals in the three-dimensional endoscope 2 is inputted, perform predetermined signal processing under control of the controlling portion 31; and a second signal processing portion 33 configured to, when an image pickup signal generated by the image pickup device 23R for right side image and passing through the CDS circuit 26R and the A/D conversion circuit 27R (hereinafter a second image pickup signal) is inputted, perform predetermined signal processing under control of the controlling portion 31.

Here, the controlling portion 31 performs control of the various circuits in the processor 3 and includes an area defining portion 31 a configured to define areas where an optical image of the object is picked up in common in the first image pickup signal representing a left side image and the second image pickup signal representing a right side image as a first common area in the left side image and a second common area in the right side image. Note that the area defining portion 31 a will be described in detail later.

Further, both of the first signal processing portion 32 and the second signal processing portion 33 perform predetermined signal processing for an image pickup signal from the image pickup device 23L or the image pickup device 23R. Each of the first signal processing portion 32 and the second signal processing portion 33 is provided with signal processing portions such as an automatic gain control circuit (AGC circuit), a white balance circuit, a gamma correction circuit, a magnification/reduction circuit and a contour emphasis circuit, which are publicly known, to perform signal processing appropriately.

Returning to FIG. 2, the processor 3 has a first light adjusting/detecting portion 34 configured to perform light adjustment/detection of the first image pickup signal processed by the first signal processing portion 32, a second light adjusting/detecting portion 35 configured to perform light adjustment/detection of the second image pickup signal processed by the second signal processing portion 33, and a 3D combining portion 50 configured to combine the first image pickup signal signal-processed by the first signal processing portion 32 and the second image pickup signal signal-processed by the second signal processing portion 33 to generate a predetermined 3D image signal.

Here, the first light adjusting/detecting portion 34 has a first photometry portion 38 configured to perform photometry of luminance of an image pickup signal which is the first image pickup signal processed by the first signal processing portion 32 under the control of the controlling portion 31 and which corresponds to the first common area in the left side image defined by the area defining portion 31 a, and output an information signal (first photometric value signal) about a first photometric value (first luminance value), and a first exposure time period controlling portion 36 configured to output a first exposure control signal for controlling an exposure time period for the image pickup device 23L according to the first luminance value obtained by photometry by the first photometry portion 38.

On the other hand, the second light adjusting/detecting portion 35 has a second photometry portion 39 configured to perform photometry of luminance of an image pickup signal which is the second image pickup signal processed by the second signal processing portion 33 and which corresponds to the second common area in the right side image defined by the area defining portion 31 a, and output an information signal (second photometric value signal) about a second photometric value (second luminance value), and a second exposure time period controlling portion 37 configured to output a second exposure control signal for controlling an exposure time period for the image pickup device 23R according to the second luminance value obtained by photometry by the second photometry portion 39.

The first exposure time period controlling portion 36 generates a control signal for electronic shutter control of the image pickup device 23L according to the first photometric value obtained by performing photometry of the luminance of the first image pickup signal and sends out the control signal to the image pickup device 23L. On the other hand, the second exposure time period controlling portion 37 generates a control signal for electronic shutter control of the image pickup device 23R according to the second photometric value obtained by performing photometry of the luminance of the second image pickup signal and sends out the control signal to the image pickup device 23R.

Furthermore, the processor 3 has a diaphragm control signal generating portion 52 configured to generate a diaphragm control signal according to the first photometric value signal and the second photometric value signal under the control of the controlling portion 31.

The diaphragm control signal generating portion 52 is adapted to generate the diaphragm control signal according to the first photometric signal and the second photometric signal corresponding to the first common area in the left side image and the second common area in the right side image defined by the area defining portion 31 a, respectively, under the control of the controlling portion 31.

Further, in the present embodiment, the processor 3 is internally provided with the light source portion 4 for emitting illuminating light to the light guide cable 16 in order to supply the illuminating light to the three-dimensional endoscope 2.

The light source portion 4 is configured, being provided with a lamp 42, a diaphragm 43, a lens 44 and a light source controlling portion 41. Illuminating light from the lamp 42 is emitted toward the lens 44 via the diaphragm 43 which is controlled by the light source controlling portion 41. Further, the lens 44 is adapted to condense light to a proximal end portion of the light guide cable 16.

Furthermore, the light condensed to the proximal end portion of the light guide cable 16 is emitted from a distal end portion of the light guide cable 16 after being transmitted through the light guide cable 16, as illuminating light supplied to the three-dimensional endoscope 2.

The light source controlling portion 41 is adapted to control the diaphragm 43 based on the diaphragm control signal generated by the diaphragm control signal generating portion 52.

That is, in the present first embodiment, an amount of illuminating light is controlled by controlling the diaphragm 43 by the light source controlling portion 41 based on the diaphragm control signal generated according to the first photometric signal and the second photometric signal.

Thus, in the endoscope system of the present first embodiment, first, an exposure time period for an image pickup signal is controlled separately for the image pickup device 23L and the image pickup device 23R by the first light adjusting/detecting portion 34 and the second light adjusting/detecting portion 35, respectively, as described above to perform control so that the luminance values of the first image pickup signal and the second image pickup signal are equalized.

On the other hand, the endoscope system of the present embodiment is adapted to perform light adjustment of a light source by generating a diaphragm control signal by the diaphragm control signal generating portion 52 according to the first photometric value signal or the second photometric value signal detected by the first photometry portion 38 and the second photometry portion 39 of the first light adjusting/detecting portion 34 and the second light adjusting/detecting portion 35, and controlling the diaphragm 43 of the light source portion 4 by the diaphragm control signal.

<Process by Area Defining Portion>

FIG. 5 is a diagram showing operation of the area defining portion in the endoscope system of the first embodiment; and FIG. 6 is a diagram showing a 3D composite image generation process in a conventional three-dimensional endoscope system.

Here, description will be made on a light adjustment/detection process for left and right images at time of generating an ordinary 3D composite image with reference to FIG. 6.

Generally, on left and right images mutually having parallax (in FIG. 6, a left side image 70L and a right side image 70R) of a three-dimensional endoscope, a deviation occurs in a left and right direction on left and right ends of each of the left and right images due to the parallax as shown in FIG. 6.

Note that it is assumed that, in FIG. 6, the left side image 70L and the right side image 70R are 3D-combined, and a 3D composite image 70S is generated and displayed on a predetermined monitor.

Further, in FIG. 6, reference numeral 72 in the left side image 70L and the right side image 70R denotes an optical image of an object to be picked up in common in left and right optical systems. Further, reference numeral 74 in FIG. 6 denotes coordinate points schematically showing positions separated from the respective object images 72 in a same direction and by a same distance in the left side image 70L and the right side image 70R.

Here, it is assumed that, in the three-dimensional endoscope, light adjustment/detection is performed for each of the left side image 70L and the right side image 70R described above on the whole screen. Then, for example, as shown in FIG. 6, when a pair of forceps 73 is inserted from a right side end in both of the left side image 70L and the right side image 70R, a degree of advance of a distal end portion of the pair of forceps 73 at a right side edge portion looks different in the left side image 70L and the right side image 70R because the left side image 70L and the right side image 70R have parallax.

More specifically, an exposed part of the distal end portion of the pair of forceps 73 in the right side image 70R looks relatively larger than that of the pair of forceps 73 in the left side image 70L as shown in FIG. 6.

Since the distal end portion of the pair of forceps 73 as described above is generally configured with a member with a high reflectivity, it is assumed that such an object with a high reflectivity significantly influences light adjustment/detection.

Therefore, the right side image 70R is detected relatively brighter than the left side image 70L in the situation described above, and, if light adjustment control is performed to cause a whole 3D-combined screen to be of a target brightness, difference occurs in brightness of an object portion at an almost central part of the screen. More specifically, as for a central part of the screen, there is a possibility that the right side image 70R becomes darker.

The invention of the present application has been made in view of such a point and provides an image pickup system capable of performing appropriate exposure control even if a large deviation occurs between luminance values of end portions in a left and right direction in two left and right field-of-view ranges, in a three-dimensional endoscope system capable of acquiring two left and right picked-up images having parallax.

A process for defining a common area by the area defining portion of the present embodiment will be described below with reference to FIGS. 2 to 5.

As described above, in the present embodiment, the controlling portion 31 of the processor 3 performs control of the various circuits in the processor 3 and has the area defining portion 31 a.

As shown in FIG. 5, the area defining portion 31 a defines areas where an optical image of the object is picked up in common in a first image pickup signal representing a left side image 60L, which has been processed by the first signal processing portion 32, and a second image pickup signal representing a right side image 60R, which has been processed by the second signal processing portion 33, as a first common area 61L in the left side image 60L and a second common area 61R in the right side image 60R.

Note that, in FIG. 5 also, reference numeral 62 in the left side image 60L and the right side image 60R denotes an optical image of an object to be picked up in common in the left and right optical systems similar to in FIG. 6. Further, reference numeral 64 in FIG. 5 denotes coordinate points schematically showing positions separated from the respective object images 62 in a same direction and by a same distance in the left side image 60L and the right side image 60R.

More specifically, the area defining portion 31 a defines areas in which object images picked up by the left-side image pickup unit 21L and the right-side image pickup unit 21R are displayed mutually in common in the left side image 60L and the right side image 60R as the first common area 61L and the second common area 61R, respectively.

<Light Adjustment/Detection Process in Common Area>

Further, in the present embodiment, the first common area 61L and the second common area 61R correspond to areas where light adjustment/detection is performed in the left side image 60L and the right side image 60R, respectively.

Then, under the control of the controlling portion 31, the first photometry portion 38 of the first light adjusting/detecting portion 34 performs photometry of a luminance of an image pickup signal which is the first image pickup signal processed by the first signal processing portion 32 and which corresponds to the first common area 61L in the left side image 60L defined by the area defining portion 31 a, and outputs an information signal (first photometric value signal) about a first photometric value (first luminance value).

Further, the first exposure time period controlling portion 36 outputs a first exposure control signal for controlling an exposure time period to the image pickup device 23L according to the first luminance value obtained by photometry by the first photometry portion 38.

On the other hand, under the control of the controlling portion 31, the second photometry portion 39 of the second light adjusting/detecting portion 35 performs photometry of luminance of an image pickup signal which is the second image pickup signal processed by the second signal processing portion 33 and which corresponds to the second common area 61R in the right side image 60R defined by the area defining portion 31 a, and outputs an information signal (second photometric value signal) about a second photometric value (second luminance value).

Further, the second exposure time period controlling portion 37 outputs a second exposure control signal for controlling an exposure time period to the image pickup device 23R according to the second luminance value obtained by photometry by the second photometry portion 39.

Then, the first exposure time period controlling portion 36 generates a control signal for electronic shutter control of the image pickup device 23L according to the first photometric value obtained by performing photometry of the luminance of the first image pickup signal in the first common area 61L and sends out the control signal to the image pickup device 23L.

On the other hand, the second exposure time period controlling portion 37 generates a control signal for electronic shutter control of the image pickup device 23R according to the second photometric value obtained by performing photometry of the luminance of the second image pickup signal in the second common area 61R and sends out the control signal to the image pickup device 23R.

Furthermore, the processor 3 has the diaphragm control signal generating portion 52 configured to generate a diaphragm control signal according to the first photometric value signal and the second photometric value signal under the control of the controlling portion 31.

Further, the diaphragm control signal generating portion 52 generates a diaphragm control signal according to the first photometric signal and the second photometric signal corresponding to the first common area 61L in the left side image and the second common area 61R in the right side image, respectively, defined by the area defining portion 31 a, respectively, under the control of the controlling portion 31.

After that, the image combining portion 35 of the present embodiment performs a process for combining the first image pickup signal representing the left side image 60L, which has been processed by the first signal processing portion 32, and the second image pickup signal representing the right side image 60R, which has been processed by the second signal processing portion 33, under the control of the controlling portion 31 to generate a 3D composite image 60S as shown in FIG. 5, and outputs a composite image signal of the 3D composite image 60S to the monitor 5.

Here, in the endoscope system of the present embodiment configured as described above, suppose that, for example, a pair of forceps 63 is inserted from a right side end of each of both of the left side image 60L and the right side image 60R as shown in FIG. 5.

Even in such a situation, that is, even in a case where a degree of advance of a distal end portion of the pair of forceps 63 at a right side edge portion differs between mutual field-of-view ranges of the left side image 60L and the right side image 60R, and a reflectivity of the distal end portion of the pair of forceps 63 differs in the left side image 60L and the right side image 60R, an operation/effect is achieved in that brightness deviation between the left side image 60L and the right side image 60R is eliminated, and light adjustment is performed to obtain appropriate brightness in the endoscope system of the present embodiment because the first common area 61L and the second common area 61R, which are a common area, are defined as light adjustment/detection ranges in the left side image 60L and the right side image 60R.

As described above, according to the present embodiment, it is possible to provide an image pickup system and a signal processing apparatus that are capable of performing appropriate exposure control even if a large deviation occurs between luminance values of end portions in a left and right direction in two left and right field-of-view ranges, in a three-dimensional endoscope system capable of acquiring two left and right picked-up images having parallax.

Note that the present invention is not limited to the embodiment described above as it is, and it is possible to modify and embody components within a range not departing from the spirit of the invention at an implementation stage. Further, it is possible to form various aspects of the invention by an appropriate combination among the plurality of components disclosed in the above embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, components among different embodiments may be appropriately combined. 

What is claimed is:
 1. An image pickup system comprising: a camera comprising: a first image pickup unit configured to pick up an optical image of an object and generate a first image pickup signal representing a first image; and a second image pickup unit configured to pick up an optical image of the object and generate a second image pickup signal representing a second image having parallax relative to the first image; and a processor comprising hardware wherein the processor is configured to: define areas where an optical image of the object is picked up in common in the first image and the second image as a first common area in the first image and a second common area in the second image, respectively; detect brightness of an image in the defined first common area in the first image; detect brightness of an image in the defined second common area in the second image; adjust brightness of the first image based on the brightness of the image in the first common area; and adjust brightness of the second image based on the brightness of the image in the second common area.
 2. The image pickup system according to claim 1, wherein the first image pickup unit comprises an image pickup optical system for left eye and an image pickup device for left eye arranged at an image forming position of the image pickup optical system for left eye and is configured to generate the first image pickup signal representing a left side image as the first image; and the second image pickup unit comprises an image pickup optical system for right eye and an image pickup device for right eye arranged at an image forming position of the image pickup optical system for right eye and is configured to generate the second image pickup signal representing a right side image as the second image.
 3. The image pickup system according to claim 2, wherein the processor is further configured to define the areas where the optical image of the object is picked up in common in the left side image and the right side image as the first common area in the left side image and the second common area in the right side image.
 4. The image pickup system according to claim 2, wherein the processor is further configured to: control an exposure time period of the image pickup device for left eye at time of adjusting the brightness of the first image; and control an exposure time period of the image pickup device for right eye at time of adjusting the brightness of the second image.
 5. The image pickup system according to claim 1, further comprising: a diaphragm configured to restrict an amount of light incident on the first and second image pickup devices; wherein the processor is further configured to: control the diaphragm based on the brightness of the image in the first common area and the brightness of the image in the second common area.
 6. The image pickup system according to claim 5, further comprising a light source configured to emit illuminating light to the object; wherein the diaphragm is provided on a route for emitting the illuminating light from the light source to the object.
 7. The image pickup system according to claim 2, wherein the image pickup device for left eye and the image pickup device for right eye are separate bodies.
 8. The image pickup system according to claim 2, wherein the image pickup device for left eye and the image pickup device for right eye are configured with one image pickup device, and an optical image by the image pickup optical system for left eye and an optical image by the image pickup optical system for right eye are formed in different areas on a same image pickup surface of the one image pickup device.
 9. A signal processing apparatus configured to process a first image picked up by a first image pickup unit and a second image picked up by a second image pickup unit, the second image having parallax relative to the first image, and the signal processing apparatus comprising a processor comprising hardware; wherein the processor is configured to: define areas where an optical image of an object is picked up in common in the first image and the second image as a first common area in the first image and a second common area in the second image, respectively; detect brightness of an image in the defined first common area; detect brightness of an image in the defined second common area; adjust brightness of the first image based on the brightness of the image in the first common area; and adjust brightness of the second image based on the brightness of the image in the second common area. 